Field of the Invention
The present invention relates to a process for preparing a chemical liquid of a silylating agent and a surface treatment method.
Related Art
Recently, there is an increasing tendency that semiconductor devices are highly integrated and have a finer pattern, and thus, the miniaturization and high aspect ratio of the pattern is progressing. However, meanwhile, there is a problem such as a so-called pattern collapse. The pattern collapse is a phenomenon that when many patterns are formed in parallel on the substrate, the adjacent patterns are so close that they lean against each other, and thus, in some cases, the patterns are broken from the base part. If such pattern collapse occurs, the desired product cannot be obtained and therefore the yield and reliability of the product are decreased.
The “pattern” used herein includes both of a “resist pattern” to be formed on a substrate by a lithography process (light exposure and developing processes) as a semiconductor manufacturing process and an “inorganic pattern” to be formed by an etching process of the substrate after the lithography process. The modification method on the surface of the substrate according to the present invention is effective for the treatment of the “inorganic pattern” among these patterns.
It is believed that the pattern collapse is caused by the surface tension of the rinse liquid when the rinse liquid is dried off in the rinsing treatment by pure water or the like after the pattern is formed. In other words, at the time of removing the rinse liquid in the drying process, the stress between the patterns based on the surface tension of the rinse liquid is affected, and thus, pattern collapse is caused.
Accordingly, if the surface of the pattern can be hydrophobized to enhance a contact angle of a rinsing liquid, a force applied to between patterns in a drying process after rinsing can be reduced, making it possible to prevent pattern collapse. Furthermore, the larger aspect ratio of the pattern increases the force applied to between the patterns, and tends to improve the effect of suppressing pattern collapse by means of hydrophobization.
Accordingly, a surface treatment method has been adopted of exposing a substrate surface to a chemical liquid of a silylating agent to render the surface water-repellent or hydrophobic (for example, Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2010-114414